The invention relates to a relief-valve construction, wherein a sensed threshold of pressure of a pressure fluid is operative to open the valve and thereby vent the pressure fluid.
Conventional practice in relief-valve construction is to provide a valve member on the downstream side of its seat, the valve member being spring-biased to its seating position of valve closure. Pressure acting on the valve member must exceed the spring bias if the valve is to be cracked, for a venting flow of fluid under pressure. But once cracked at onset of a relieving flow, the pressure and fluid density conditions determining whether and to what extent the valve is to open can be almost anything, being on the downstream side of the seat, and therefore subject to fluctuating pressure differentials on the downstream side of the seat. Relief-valve operation therefore can be spasmodic, manifesting itself in chatter.